Pyran is an important industrial raw material of perfume. For example, α-phenyl-dihydropyran can be converted by reductive opening of its pyran ring into 5-phenyl-3-methylpentanol particularly important as a perfume. Further, tetrahydro-4-hydroxy-2-isobutyl-4-methyl-pyran itself is useful as a perfume.
Swiss Patent No. 655932 discloses a process for producing a pyran derivative by reacting an aromatic aldehyde with isoprenol in the presence of an acidic dehydrating agent.
JP-A 11-29564 discloses a process for producing a pyran derivative by reacting an aldehyde with a diene compound such as isoprene in the presence of a Lewis acid catalyst.